This invention relates generally to a fluid imaging method and more particularly, to MR angiography or in other words, a method of obtaining a blood flow image inside a human body by utilizing nuclear magnetic resonance.
A typical specific example of conventional blood flow imaging methods using an MRI apparatus is the one that extracts only a blood flow by subtraction of an image obtained by a flow-sensitive pulse sequence and an image obtained by a flow-insensitive pulse sequence. As typified by this method, those methods which obtain an intended image from a plurality of images having mutually different properties are generally known. One of such methods is discussed in "Magnetic Resonance In Medicine", Vol. 12, pp. 1-13, 1989. This method obtains the blood flow image by subtraction of the images obtained by two measurements in the case where magnetic field waveforms of a readout gradient magnetic field are represented by flow encode pulses wherein the phase change of magnetization due to a flow is emphasized, and in the case where they are represented by flow compensate pulses wherein the phase change of magnetization due to the flow is corrected.
On the other hand, a half encode method is known as the method of reducing by half the data sampling number without reducing resolution. This method measures only the half of a Fourier space and obtains the rest of the data by calculation by utilizing the fact that measurement data have mutually conjugate complex relation on the Fourier space if the image data are the real number. This method is described in detail in "Radiology", Vol. 161, pp. 527-531, 1986, for example.